DESCRIPTION.—The body depressed and wide—the head
triangular, the muzzle rather acute. Nostrils prominent and nearly
round. Scales of the head very small and numerous; those of the temple
rhomboidal and imbricated. There are four series of small irregular
scales between the labial and sub-orbitar. The sides of the neck are
wholly granular; the scales of the body very small; those of the upper
parts rhomboidal, flat with very low carina, and obtuse at the
apex—beneath they are also small and rhomboidal; the posterior surface
of the thighs is granular, but, as in some other species, there is,
near the groin, a distinct patch of imbricated scales like those of the
inferior surface. The tail is broad to some distance from the origin,
and then tapers to the extremity. The scales of the tail are rather
small, short and obtuse.

The anterior extremity placed against the sides
reaches about two-thirds the distance towards the posterior, and the
latter reaches forwards to the shoulder.

The ground colour of this species is gray, with
numerous small black spots, some of which are bordered with white. The
under parts are white, and in one specimen in Mr. Darwin's collection
there are on the belly numerous distinct small black spots. His
description of the colours is as follows:—"Colours above singularly
mottled. The small scales are coloured brown, white, yellowish red and
blue, all dirty, and the brown forming symmetrical clouds. Beneath
white, with regular spots of brown on the belly."

Found at Bahia Blanca, on the northern confines of
Patagonia. The following remarks of Mr. Darwin on the habits of this
species are very interesting. "In its depressed form and general
appearance it partakes of some of the characters

of the Geckos. Its habits are singular. It lives on
the dry sand of the beach, at some distance from the vegetation, and
the colour of the body much resembles that of the sand. When frightened
it depresses its body, stretches out its legs, and closing its eyes
tries to escape detection. If pursued it buries itself with great
quickness in the sand; but as its legs are short, it cannot run very
swiftly."

DESCRIPTION.—The scales of the head are narrow,
closely imbricated, strongly but not acutely carinated, and the
anterior ones arranged in somewhat of a radiating direction from the
muzzle. There is but a single series of scales between those of the
upper lip and the orbit, and these, together with all the scales about
the head, partake of the carinated and elongated character already
described. A single strong triangular scale and two smaller ones are
placed on the anterior margin of the ear, which is narrow, oval and
reniform. The scales of the temples and sides of the neck are
rhomboidal, acute, carinated and imbricated. There is a longitudinal
fold on each side of the neck and a transverse one anterior to the
shoulder, behind which is a deep depression. The scales of the back and
side are prominently and acutely carinated, those of the central line
being rather more prominent than the others; and above this there is on
each side a marked longitudinal lateral crest extending from beneath
the eyes to the base of the tail. The scales constituting these crests
are very prominent, narrow and acutely carinated. The scales of the
belly are also imbricated and rhomboidal, but flat; those of the under
surface of the hands and feet are carinated; and those of the toes have
three carinæ. The body is somewhat depressed as is the tail at its
commencement, becoming more rounded and rather abruptly smaller at some
distance from its origin. The fore-foot reaches to about two-thirds of
the distance from the shoulder to the side, and the hinder extremity
thus placed extends to the shoulder.

The colours of this most elegant of all the species
of the genus are very beautiful. "This is the most beautiful lizard,"
says Mr. Darwin, "I have ever seen; the back has three rows of
regular oblong marks of a rich brown, the other scales symmetrically
coloured either ash or light brown; many of them of a bright emerald
green; beneath pearly, with semilunar spots of brilliant orange on the
throat." I find in the specimens I have examined that the pectinated
lateral crests are white, and the brown oblong marks of the back are
bordered with a similar colour. There are always three white transverse
lines across the head.

This species, as has been observed by M. Bibron, who
first described it, may be at once distinguished from every other by
the character of the scales of the head, which, instead of lying flat,
with the edges in contact, are all of them imbricated and carinated.
Another obvious distinguishing character, is the narrow line of
prominent scales running the whole length of the body on each side,
forming a sort of pectinated lateral crest, from which
circumstance it has derived its name.

The new genus which I have thus defined, resembles
very closely, in most of its characters, the genus Leiosaurus of
Bibron; from which, indeed, it scarcely differs, excepting in the
absence of palatine teeth, and in the form of the suborbitar plates,
which in Leiosaurus are all distinct, and of nearly equal
size: whereas, in the present genus, three of these are united to form
one plate, resembling that in Proctotretus, and some other Agamidæ.
In other respects the genera are very closely allied; but the
existence or non-existence of palatine teeth, is a character of so much
importance, that it appeared to me,—and in this opinion I am supported
by M. Bibron, who examined the specimens with me,—that they should be
considered as distinct. Both the genera are natives of South America.
Of Leiosaurus Bellii (Bibr.) the only known specimens were
presented to me by Capt. King, who obtained them during his survey,
from whom also I obtained specimens of one of the species of the
present genus, D. Bibronii.

DESCRIPTION.—Head short, almost equilaterally
triangular, rising obliquely from the muzzle to the vertex, then
flattened. Nostrils large, round, each placed in front of the
supra-orbital crest, and in a line between it and the centre of the
muzzle. The ears are small, oval, the margin simple, and the membrana
tympani superficial. The neck is considerably contracted; it has a
longitudinal fold on each side formed by the confluence of two others,
one of which arises from behind the angle of the mouth, and the other
from above the ear, which is, as it were, enclosed between them; they
coalesce a little behind the ear. There is also a distinct transverse
fold on the throat, very similar to that in Leiosaurus Bellii. The
body is moderately thick, somewhat depressed, and without the slightest
appearance of a longitudinal crest, or any elevation along the median
line. The tail is somewhat longer than the head and body, nearly round
and tapering almost evenly from its origin to the apex. The fore legs
are short and moderately robust, the toes short, nearly equal; the
hinder legs moderately long. The former when placed against the sides,
do not reach the thighs by nearly a third of the distance between the
two limbs; the latter when directed forwards, just reach the axillæ.
The cloacal covering is semilunar, turgid, and the margin quite simple.

Scales covering the upper surface of the head
numerous, rounded, and considerably elevated; those between the two
supra-orbital semicircles are in a double series. The occipital plate
is oval, raised from the margin, hollowed immediately around the centre
which is again raised like a minute tubercle. Above the labial scales,
is a series of equal, rounded, oblong scales, and between these and the
principal suborbital is a single series of smaller ones. Scales of the
whole of the upper and lateral parts of the neck and body extremely
small, slightly elevated, passing at the sides into a flatter and more
expanded form. Those of the whole of the under parts are quite flat and
imbricated. Beneath the anterior parts of the lower jaw, and behind the
broad mental scales, are a series of flat, hexagonal scales on each
side, passing backwards and outwards, the front pair large and oblong
and the others diminishing by degrees. The scales of the throat are
very small, those on the fold larger and acutely rhomboidal. The scales
of the anterior part of the belly are also rhomboidal and those of the
posterior portion hexagonal or nearly quadrate. The tail is covered by
scales disposed in whorls, those on the median line beneath being
larger than the others. Beneath each toe is a series of transverse
hexagonal imbricated scales.

The colours and markings of this species are very
difficult to be described, on account of the great irregularity of
their disposition. The ground colour of the head is yellow, passing
into grey on the back part. The anterior part has several small spots
of a dark brown colour, and there is a larger one on each orbit,
another between the eye and the ear, and others on the back part of the
head extending to the neck. The middle of the back is reddish yellow, on

each side bluish gray, passing beneath into
yellowish white. A series of very irregular transverse spots cross the
yellow median portion of the back, and there are others on the sides;
and these two series becoming confluent on the tail, form, with the
yellow ground, alternate half rings of the two colours. The upper part
of the legs has similar bands. The whole of the throat, belly, and
inferior surface of the limbs and tail are yellowish white. There are
numerous small blackish spots over these parts which are more distinct
and linear on the throat, and becoming paler, smaller and round on the
belly.

DESCRIPTION.—Head thick and clumsy, longer than it
is broad, muzzle obtuse, supra-orbital arches slightly elevated.
Nostrils as in the former species, in size, form, and situation. Ears
sub-triangular, the margin simple. Neck considerably contracted, with a
longitudinal fold on each side, and a distinct transverse fold on the
throat. Body rather broad, slightly depressed, perfectly even, without
any central crest or elevation. The tail is shorter than the head and
body, slightly triangular at its base, tapering regularly to its
extremity. Limbs of moderate length; the toes of each foot longer than
in D. Bibronii, and those of the fore-feet more unequal, the
third being the longest, then the fourth, the second, the fifth, and
the first. The fore-legs placed against the side reaches to about
two-thirds of the distance between the shoulder and thigh; the hinder
foot placed in the same manner reaches to the axilla.

The scales of the head are quite flat, a character
in which this species differs remarkably from the former, although in
their number and arrangement they are very similar. The occipital scale
is flat and hexagonal. Between the labial scales and the suborbital,
there are, in addition to the regular series of larger supralabial
scales, at least three distinct series of smaller ones; whereas in D.
Darwinii there is but one.

The scales of the temples, the neck, the body, the limbs and the
tail, are similar to those

of the former species in general form and
arrangement, excepting that they are smaller and less elevated. Those
beneath the anterior part of the lower jaw are much smaller; but the
rest on the under parts are similar to the former.

The head is of a dull light-brown colour, with a few
obscure darker spots. The general ground colour of the back is "bluish
gray, tinged with rust colour;" there are five transverse bands across
the back, which are composed principally of numerous, close, small,
dark-brown spots, on a bluish-gray ground, darker than the intervals,
and without any red tinge; and each band is marked on the posterior
margin with strongly defined semilunar indentations, bordered with
yellowish-white, or bright yellow. These bands are continued on the
tail, where they become half-rings.

This species was first described by Mons. Bibron in
the "Histoire des Reptiles," and so fully as not to require any
detailed
account of its characters here. It has not, however, hitherto been
figured, and it is thought very desirable to embrace so good an
opportunity of giving a representation of so interesting an animal. Its
most important structural peculiarities will be alluded to in the
account of the next species, which is an aquatic form, whilst the
present is strictly terrestrial. The toes are long, compared with those
of the other, and so unequal as to constitute essentially an ambulatory
form.

By Mr. Darwin's observations we are now enabled
fully to confirm Mons. Bibron's suggestion, that this species was from
the Galapagos, and to establish the genus as strictly appertaining to
that curious and interesting locality.

I established the genus Amblyrynchus nearly
eighteen years ago, from a stuffed specimen of the present species,
which had been obtained by Mr. Bullock, Jun., in Mexico. I had never
seen another specimen, until Mr. Darwin brought home a young one from
the Galapagos, in excellent preservation in spirits, and thus
established its true habitat, and enabled me to correct those errors in
my description which arose from drying and bad stuffing. Mons. Bibron
also took his description from my specimen, and thus necessarily fell
into the same mistakes, of which the most important are those which
relate to the form of the tail, and the structure of the feet. Thus the
tail is described as "round, excepting towards the extremity, where it
is flattened at the sides," whereas it is in fact much compressed
throughout its whole length; and with regard to the toes no mention is
made of their being partially united by a web or fold of skin, which is
the case both on the anterior and posterior feet. These two characters
so obviously point out a power of swimming, that the aquatic habits of
the species might at once have been predicated, and it is exceedingly
interesting to find, from Mr. Darwin's observations, that such is
really the case. We have, therefore, two distinct forms—distinct
equally in their structure and in their habits—in the two species now
described; the one, A. Demarlii, being truly terrestrial,
with lengthened, unequal, and distinctly separated toes and a round
tail, and the present species as truly amphibious, having short, nearly
equal and webbed toes, and a compressed tail.

A very interesting account of their habits, &c,
is given by Mr. Darwin in his delightful Journal of the Voyage of the
Beagle, p. 466 to 472, to which the reader is referred, and which
exactly accords with the peculiarities of their respective structure
just alluded to.

It is remarkable also, that whereas Amblyrynchus
cristatus inhabits the coasts of all the islands, the other
species is found only in the central portion of the group.

DESCRIPTION.—Head, viewed from above, forming a
nearly equilateral triangle, covered with irregular slightly raised
scales. Supra-orbital ridge prominent, and covered with a series of
elongated and imbricated scales. Occipital plate large, pentagonal,
notched at its posterior margin. The anterior margin of the auditory
passage is strongly quadridentate, from the existence of four long and
rather narrow scales. Scales of the temple obtusely carinated, not
imbricated; those of the back strongly and acutely carinated and
disposed in numerous rows, converging backwards towards the dorsal
crest. Ventral scales rhomboidal, not carinated. Dorsal crest elevated,
composed of flat vertical scales, so closely placed as to constitute an
almost continuous line, extending from the neck to the end of the tail.
Tail somewhat compressed at the base, becoming nearly round towards the
middle. Scales beneath the feet and toes carinated.

COLOUR.—The colour of this species is thus stated in
Mr. Darwin's notes:—"Upper part clove brown, passing into black brown
with black spots. Sides slightly tinted with orange; some of the
scales of the crest near the head are white; belly nearly white; the
whole of the throat before the fore legs glossy black. This is the most
common variety in the Archipelago. The black spots are not unfrequently
placed in waved transverse bars, and are sometimes arranged
longitudinally.

Of this species, one of the most beautiful in the
whole order of Saurians, Mr. Darwin obtained numerous specimens, one
only of which is fully adult. In the younger individuals the dorsal
crest is low and almost inconspicuous. It differs very materially from
either of the two species previously described, and I have dedicated it
to Mr. Gray, who first distinguished the genus. Mons. Bibron, unaware
that Mr. Gray had already constituted the genus under the name Leiocephalus,
named it Holotropis. I have, however, retained the former
name, as having the claim of priority.

The propinquity of this genus both to Oplura and
to Doryphorus is very obvious. It differs, however, from
both
in several structural characters. From the former in the absence of
denticulations on the anterior margin of the ear, and of a nuchal
crest; from the latter in the presence of palatine teeth. Its place is
probably between these two genera.

CENTRURA FLAGELLIFER. Mihi.

PLATE XIII.—FIG.2.

DESCRIPTION.—Head almost equilaterally triangular,
the muzzle rounded; scales of the head small, nearly equal, rounded,
not imbricated, those of the temples subconical; nostrils round, large,
confined to the nasal scales. Ears rather large, the tympanum lying
beneath the surface, and partly concealed by an anterior fold of skin,
which is not denticulated, as in Oplura. Skin of the neck
folded at the sides, that of the body flaccid, and with strongly marked
lateral folds, extending from the shoulder to the thigh. Scales of the
neck and back very small, round, slightly convex, very smooth. Skin of
the throat rugose, with a transverse pectoral fold not very strongly
marked. Scales of the throat similar to those of the back; those of the
belly broader and less convex; all perfectly smooth. Tail about the
length of the head and body, flattened at the base, then round,
surrounded with strong spinous verticillated scales, of which there are
about fifty circles; beneath smooth. Legs of moderate length, strong,
covered with small conical, imbricated scales. The toes compressed
towards the extremity, and terminated with a strong, short, compressed
nail.

COLOUR.—The colour can only be partially described, as the specimen
has been long in spirits. It

This species was first brought from Coquimbo by
Gaudichaud, after whom it was named by Mons. Bibron, who described it
in his work; but as one specimen alone exists in the French National
Collection, and as the species has never been figured, it is thought
desirable that a figure should be given in the present work. The
characters above given sufficiently distinguish it from all other
species; but for a detailed description, the reader is referred to the
"Histoire des Reptiles" above quoted.

The specimens brought home by Mr. Darwin were from
Port Desire, in Patagonia, and the following observations occur in his
MS. notes:—"Centre of the back yellowish brown, sometimes with a
strong tinge of dark green; sides clouded with blackish brown; in
very great numbers under stones; makes a grating noise when taken hold
of; after death loses its darker colours.

"A specimen being kept for some days in a tin box,
changed colour into an uniform grey, without the black cloudings. I
thought I noticed some change after catching and bringing home these
animals, but could observe no instantaneous change."

I have considered these specimens as belonging to
the species to which I have assigned them, because they exactly agree
with Mons. Bibron's description. It is, however, very possible that an
opportunity of comparing them with those obtained by Gaudichaud, would
show them to be distinct, as it rarely happens that the same species of
reptile is found on the opposite sides of the American Continent.

GENUS—NAULTINUS. Gray.

NAULTINUS GRAYII.

PLATE XIV.—FIG. 2.

Omninò viridis; fronte
subconcavo; squamulis
capitis planis.

DESCRIPTION.—Head thick, swollen across the
posterior part, concave between the eyes, and forwards nearly to the
snout, which is rounded. Scales of the head larger towards the fore
part, nearly flat. Eyes round, large; ears longitudinally oval. Body
covered with small nearly equal scales. Tail round, one-fifth longer
than the body. Limbs short, the anterior, when placed against the side,
reaching but little more than half way to the thigh; the posterior
reaching about two-thirds the distance towards the shoulder. Toes
short; on the anterior foot the first is the shortest, then the second,
the fifth, and the fourth; on the posterior increasing in the same
series; all compressed towards the extremity, and all furnished with
small curved close claws.

The colour is a fine green.

It was taken at the Bay of Islands, New Zealand. It
lives on trees, and is said to make a laughing noise.

This species greatly resembles Naultinus
Elegans* of Mr. Gray, of which a beautiful specimen is
in the British Museum. Upon a comparison of the two,

however, I find that they differ in the following
particulars. In the present species the head is concave between the
eyes, and forwards nearly to the snout; in the other, this part is
quite plain; the scales of the head in this species are flat; in the
other they are convex. The colour of this species is uniformly green,
whereas N. Elegans has several markings of a yellow colour,
each distinctly bordered with black.

DESCRIPTION.—Head very narrow, much elongated and
pointed, the vertex flattened; nostrils rather large, open, round,
directed laterally, and placed in the centre of the naso-rostral plate;
superciliary plates three in number, the central one the largest;
suprahumeral scales rhomboidal, imbricated, not broader than long, in
four series; those of the arm transversely hexagonal; the anterior
surface of the thigh, and the inferior of the leg, covered with large
hexagonal, somewhat imbricated, scales; caudal scales above quadrate,
longer than broad, with a strong medial carina, and the lateral margins
slightly raised; beneath smooth; tail very long. Anterior extremity
placed against the body, reaching rather more than half way to the
thigh; posterior extremity extending forwards nearly to the ear.

COLOUR.—The upper surface of this beautiful species
is dark brown or blackish, with nine distinct white or yellowish
longitudinal fasciæ extending through the whole length of the neck and
body; tail with four of these lines. Under parts white.

Found at Bahia Blanca by Mr. Darwin. The specimens
are probably all of them very young; hence the longitudinal lines can
scarcely be considered as permanent, as most species of the genus are
beautifully lineated in the young state. The length of the tail, with
its carinated scales, the general elegance of the form, the gracile
form of the head, and the neat and distinct arrangement of the colours,
render this one of the most beautiful species of this elegant genus.

The description of the colours given above, being
from specimens which have been long in spirits, it is necessary to
state that Mr. Darwin has the following notice respecting one of
them—"On the sides two dark red streaks; tail red."

After a careful examination of the data from which
the different synonyms of this species, and of Gerrhosaurus
flavigularis, Bibr., have been derived, I am inclined to agree
with this author, that the present is the true Scincus sepiformis of
Schneider, and of Merrem, and not Scincus flavigularis as
supposed by Wagler, Weigmann, and Gray. It is very fully described by
Bibron in the "Histoire Naturelle des Reptiles," but it has not
hitherto been figured. There is no notice of it in Mr. Darwin's notes,
further than its having been obtained at the Cape of Good Hope.

As I have not the work of the lamented Dr. Cocteau
by me, I quote the above reference from M. Bibron's work, in which this
species is fully described. It differs from the other species of this
curious genus in many minute characters of the scaling of the head, but
the most tangible and obvious distinctive character consists in the
number of series of scales, which does not exceed twenty-four, all
around the body, whilst in the others, they amount to thirty-four or
thirty-eight. It would appear that it is liable to some considerable
diversity in colour and markings. That which M. Bibron describes, has
"the head of a yellowish grey, the whole of the upper part of the body
olive grey, and the inferior part whitish grey." The specimen in the
collection of the Zoological Society has the whole upper part of a
brownish grey, with twelve black lines extending from the neck along
the back and tail, corresponding with the sutures of the longitudinal
series of scales. The under surface of the tail is marked by about
thirty transverse, interrupted, black bands. The following is the
description given by Mr. Darwin from his specimen when taken,—"Scales
on the centre of the back light greenish brown, edged on their sides
with black; scales on the sides of the body above greyer and with less
black, below reddish: belly yellow, with numerous narrow, irregular,
waving, transverse lines of black, which are formed by the lower margin
of some of the scales being black; head above grey, beneath whitish."
Mr. Darwin adds, that the motion of the body, when crawling, resembles
that of a snake. It is not very active. Coleoptera and larvæ were
found in its stomach. "It is common in the open woods near Hobart Town
in Van Diemen's Land."

DESCRIPTION.—Head elongate, depressed. Eyes large,
not prominent. Tympanum nearly round. Palatine teeth in two simple
series, commencing at the inner side of the anterior margin of the
posterior nares, and extending towards each other in a transverse
direction, leaving between them a space of about half the length of
each. Tongue not quite as long as it is broad. Body somewhat depressed,
and with the head forming an almost uninterrupted ellipse. Skin of the
back, with several small longitudinal folds. Anterior legs, when placed
against the sides, reaching to the thigh. Fingers very slender, and of
nearly equal length. Posterior limbs fully twice as long as the head
and body. Toes extremely long and slender, and connected by a membrane
by about half their length.

COLOUR.—The general colour of the upper parts is a
rich brown, with darker brown and white markings. A white median fascia
extends the whole length of the head and body; another fascia of the
same colour and of very irregular figure on each side, passes backwards
and downwards from above the shoulders, and loses itself in the pale
colour of the abdomen. There are several smaller white lines and spots,
and others of a dark rich brown, particularly a large mark of the
latter colour behind the eye, including the tympanum. The thighs and
legs are elegantly banded with similar colours. The under side is
whitish.

DIMENSIONS.

In.

Lines.

Length

of the head and body
. . .
. . .
. . .
. . .
. . .
. . .
. . .
.

1

8

of anterior extremities
. . .
. . .
. . .
. . .
. . .
. . .
. . .

1

1

of posterior ditto
. . .
. . .
. . .
. . .
. . .
. . .
. . .
. . . .

3

7

This species was first discovered at the Cape of
Good Hope by M. Delalande, and named after him by Mons. Bibron. Mr.
Darwin found it in the same locality. It is now figured for the first
time.

This pretty species of the typical genus of the
family was described by Bibron, but has not hitherto been figured. It
was found in Mauritius, on swamps near the sea, by Mr. Darwin, who
remarks on the extraordinary height of its leaps. It has also been
found in the Seychelles, Madagascar, and the Island of Bourbon.

The genus Limnocharis is remarkable for the
existence of palatine teeth in a part of the mouth in which they have
never been observed in any other amphibian. Not only is there a small
group or line of these contiguous with the anterior margin of the
posterior nares,—a situation in which they are found in some other
genera of Ranidæ, but there is also a group of them placed
at
some distance behind the posterior margin of these openings, and close
within the rise of the maxillary arch. This genus, of which one species
only is at present known, will probably be most naturally placed
between the true Ranæ and certain of the Cystignathi.

DESCRIPTION.—Head semi-oval, depressed, as broad as
it is long. The muzzle truncated, extending beyond the lips, which it
overhangs. Tongue oval, entire, free at the posterior margin. Palatine
teeth in two parcels on each side; one consisting of very few at the
anterior and inner margin of the posterior nares, the other behind
those openings, in the angle formed by the maxillary arch and the
orbits. Posterior nares large and oval. Tympanum conspicuous, nearly
circular. Skin every where perfectly smooth, without glands or pores.
Anterior legs of moderate length and size. The fore-arm rather longer
than the upper arm. Fingers of moderate length, wholly detached. Hinder
legs little more than one-third longer than body. The toes separate,
excepting a slight rudiment of a connecting membrane at their base,
which extends, though very narrow, along their sides, the extremity
very slightly notched.

COLOUR of the upper part rich dark brown. The thighs
lighter, obscurely banded with dark brown. Under parts pale blueish
grey. The throat dotted with brown.

DIMENSIONS.

In.

Lin.

Length

of the head and body
. . .
. . .
. . .
. . .
. . .
. . .
. . .
.

1

4

of the anterior extremities
. . .
. . .
. . .
. . .
. . .
. . .
.

0

7

of the posterior extremities
. . .
. . .
. . .
. . .
. . .
. . .

1

8

Found in brooks at Rio Janeiro by Mr. Darwin, who
states that it is infested with acari; and I observe, in the specimen
under examination, several marks in the skin, from whence these have
been taken.

appearance of the tympanum, the paucity of palatine
teeth, and the total absence of an interdigital membrane on the hinder
feet. These characters being either merely comparative or unimportant,
were not considered by Bibron as sufficient to warrant a generic
separation, and I have followed him in retaining the species amongst
the Cystignathi. It was first discovered by Messrs. Quoy and
Gaimard at King George's Sound, in Australia, where it was also
obtained by Mr. Darwin. It is a beautiful species; the back being of a
rich brown colour, with a pale orange fascia extending along the sides
from the eye to the thigh, becoming bright orange on the flanks. Thighs
and legs banded with rich deep brown and bright orange.

The two species on which I have founded this genus
approach so nearly to some species of Cystignathus, that it
is
not without hesitation that I determine on considering them as typical
of a new generic form. The principal characters on which I have founded
the distinction are the position of the palatine teeth, the form of the
tongue, the concealment of the tympanum, the absence of glands and
pores on the skin, and the connexion of the base of the hinder toes by
a rudimentary palmar membrane. It is true that some of the species of Cystignathus,
as that genus is at present constituted, agree with the present
form in some or other of these particulars; but upon the whole they
are sufficiently distinct; and in fact the genus Cystignathus,
as
left by M. Bibron, appears to me to stand in need of revision and
dismemberment. The species constituting the genus now proposed, are
however both new. The genus Borborocœtes will probably
stand,
in its natural affinities, between Cystignathus and Cycloramphus,
from the latter of which it differs in the situation of the
palatine teeth, in the degree to which the hinder feet are webbed, and
the comparative length of the hinder legs. The two latter characters
are of importance as indicating a difference of habit; and we find that
Cycloramphus has proportionally short hinder limbs, with the
toes

DESCRIPTION.—Head depressed, the vertex slightly
concave between the orbits; front (space included between two lines
drawn from the anterior corner of the orbits to the point of the nose)
triangular and distinct. Nostrils lateral. Eyes rather prominent.
Tongue broad, ovate, acuminated in front, behind entire and rounded,
the posterior half and the sides detached. Palatine teeth in two oval
parcels, direct obliquely backwards and inwards, and situated at some
distance behind the line of the posterior margin of the nares. Tympanum
concealed. Body rather depressed and short. Skin smooth and without
pores or glands, excepting on the posterior and inferior surface of the
thighs, where there are some small granular elevations. Fore legs
two-thirds the length of the head and body. The fore-arm rather larger
than the upper arm. The fingers entirely separated, the third
considerably the longest. A small tubercle under each joint, and two on
the palm near the wrist. Length of the hinder legs to that of the head
and body as 5 to 3, or rather more. Toes connected only at their base.
A small tubercle under each joint, and a very depressed one at the base
of the inner toe.

COLOUR of the upper parts fuscous, with a lateral
fascia extending from the orbit nearly to the thigh, of a dark-brown
colour, bordered with whitish; and another of an elongated triangular
form on each ilium. Legs with transverse incomplete faciæ of the same
colour. Under parts grey, with numerous brown dots.

This species considerably resembles the former in
most of its characters. The palatine teeth, however, form at once a
certain and tangible distinction, and there are some minor points in
which they differ, sufficient at a glance to determine them. The head
in the present animal is broader than it is long; in the former the
breadth is only equal to its length. The palms are in this species
without conspicuous tubercles; in the other there are two, although
very small.

In colour it differs much from the former. The
general colour is a rich fuscous brown, rather paler beneath; the
flanks, the throat and belly, and the whole of the thighs and legs,
with various white markings, those of the throat and belly being the
smallest. This species was found in the forest, in Valdivia.

GENUS—PLEURODEMA. Tschudi.

I have thought it right to follow Tschudi in
separating from the genus Cystignathus of Wagler, such
species
as have large and conspicuous lumbar glands, particularly as they all
agree in possessing a much more bufonine aspect than the others. The
discovery of three new species, all agreeing in these characters with Pleurodema
Bibronii of Tschudi, increases the importance of the grounds upon
which this separation is made.

DESCRIPTION.—Head triangular, rather broader than
long. Muzzle rounded. Eyes slightly prominent. Tongue somewhat
heart-shaped, scarcely emarginated behind. Palatine teeth very few, and
with difficulty perceptible, placed in two small groups between the
posterior nares. Body thick and broad, with numerous glandular
tubercles scattered over the surface, principally on the anterior
parts, and assuming somewhat of a longitudinal arrangement. Lumbar
glands large, round, and prominent. Legs robust and short. Toes of the
fore feet wholly separate, with a small tubercle under each joint, and
two larger ones at the hinder part of the palm. Hinder toes, with a
rudimentary membrane at the base, a small tubercle under each joint;
the first and second toes very short. A conical tubercle at the inner,
and another at the outer side of the metatarsus.

COLOUR.—The upper surface is beautifully marbled
with dark olive or black, on a light-green ground; some of the markings
assume somewhat of an ocellated form, and approach to a symmetrical
arrangement. The lumbar glands are more strongly coloured than the
other parts, the centre being black, and nearly surrounded by a bright
line of very light green, or nearly white. The thighs are numerously
banded with the prevailing colours, and a tinge of orange or red.
Beneath pale; in some specimens blackish under the chin.

The aspect of this species is remarkably bufonine;
and this character is increased by the numerous glandular tubercles on
the surface of the body, and pores about the parotid region. It is,
doubtless, similar in its habits to many of the toads.

DIMENSIONS.

In.

Lin.

Length

of the head and body
. . .
. . .
. . .
. . .
. . .
. . . . .
. .

1

4

of the anterior extremities
. . .
. . .
. . .
. . .
. . .
. . .

0

8

of the posterior extremities
. . .
. . .
. . .
. . .
. . .
. . .

1

7

It was repeatedly found by Mr. Darwin at Maldonado,
near the mouth of the river La Plata.

oval groups, extending obliquely backwards and
inwards, but separated by a considerable interval. Body somewhat
depressed and elongated, with many prominent glandular tubercles, and
with pores about the parotid region. Lumbar glands of moderate size, of
an elongated oval form, and very convex. Legs rather slender, the
anterior feet with the third toe considerably the longest; a small
tubercle under each joint of all the toes, and several small
inconspicuous ones on the palm; hinder legs rather elongated, the toes
long, particularly the fourth, the first very short; a small tubercle
under each joint; the inner metatarsal tubercle prominent, the outer
one inconsiderable.

COLOUR.—The markings of this species are very
elegant and striking. The ground colour of the upper parts is a rich
brown, with darker cloudings and marks; a light yellowish longitudinal
line running all the length from the nose to the extremity of the body,
a very irregular fascia on each side of the same colour enclosing a
brown oblong spot on the upper lip, another just behind the tympanum,
and two others on the sides; there is also a brown fascia from the
extremity of the nose to each eye; the lumbar glands are black and
yellow, distinctly marked. The limbs are obscurely banded with brown
and pale yellowish. The colours in some specimens are more obscure than
in that figured, and they appear to lose their clearness with age.

The following are the colours of the brighter
individuals according to the observations of Mr. Darwin:—"Yellowish
and broccoli-brown, with darker brown marks; broad medial dorsal line,
pale gallstone yellow; lumbar glands saffron yellow and jet black."
Another specimen was "ash-grey with blackish brown marks."

DIMENSIONS.

In.

Lines.

Length

of the head and body
. . .
. . .
. . .
. . .
. . .
. . . .
. . .

1

8

of the anterior extremities
. . .
. . .
. . .
. . .
. . .
. . .

1

0

of the posterior extremities
. . .
. . .
. . .
. . .
. . .
. . .

2

4

The general habit of this species is much more in
accordance with its relation to the Ranidæ than that of
the
other species of the genus. Its general form is more elongated and
depressed, and the limbs, particularly the hinder ones, are longer in
proportion to the body. It is certainly very near Pl. Bibronii of
Tschudi, but still undoubtedly distinct.

DESCRIPTION.—Head short. Muzzle rounded. Eyes
prominent. Tongue thick, slightly heart-shaped, scarcely notched on the
posterior margin. Palatine teeth prominent, in two oval groups,
converging backwards. Tympanum rather small, perfectly round,
conspicuous. Parotid glands distinct. Body thick and broad, with small
glandular tubercles dispersed over the surface, particularly at the
anterior part. Lumbar glands extremely large, elliptic-ovate, flat.
Legs of moderate length, rather robust. Anterior toes separated,
excepting at the base; a small tubercle under each joint, and several
very small ones on the palm; hinder toes united to about half their
length, and bordered on each side to the extremity; metatarsal
tubercles prominent; soles of the hinder feet with many minute
tubercles.

COLOUR.—The upper surface of this species is of a
brownish grey colour, sometimes greenish brown or dark olive, and with
numerous irregular spots of dark-brown or black. Thighs and legs with
fasciæ of the same colour. Beneath yellowish white; in some with
numerous blackish dots under the throat.

DIMENSIONS.

In.

Lin.

Length

of the head and body
. . .
. . .
. . .
. . .
. . .
. . . .
. . .

1

8

of the anterior extremities
. . .
. . .
. . .
. . .
. . .
. . .

1

0

of the posterior extremities
. . .
. . .
. . .
. . .
. . .
. . .

2

3

Found by Mr. Darwin at Port Desire, in Patagonia,
and high up the river Santa Cruz—"probably," says Mr. Darwin, "the
most southern limit for this family."

GENUS—LEIUPERUS. Bibr.

LEIUPERUS SALARIUS. Mihi.

PLATE XVIII.—FIG. 1.

Supra nigricans, lumbis maculis 3 vel 4
nigris,
albo-marginatis.

DESCRIPTION.—The head is short, the opening of the
mouth small, the tongue rather thick, very slightly emarginate behind,
and with the posterior margin free. The eyes small; the tym-

panum not very conspicuous; there is a trace of a
parotid gland on each side of the neck. The body is rather thick, and
the limbs proportionally short. The hinder toes are only connected at
the base by a rudimentary membrane, the first four gradually increasing
in length, and placed along the side of the matatarsus, one beyond the
other; the fifth on the same line as the fourth, but not more than half
its length. The metatarsal tubercle is rather prominent, and there are
small subarticular tubercles on the toes of all the feet.

COLOUR.—The
colour of the upper parts is brownish black. On each side near the
thigh are three or four perfectly round black spots, each surrounded
with a white line. The under parts whitish.

Of this second species of a rare and remarkable
genus, one specimen only exists in Mr. Darwin's collection. It is only
the third known instance, in the family of the RANIDÆ, of the absence
of palatine teeth; the others being Oxyglossus Lima of
Tschudi, and Leiuperus marmoratus of Bibron. The present
genus
must be considered as nearly approaching the family of the BUFONIDÆ in
the absence of palatine and the extreme minuteness of the maxillary
teeth, in the extremely small gape of the mouth, the thick form of the
body, the shortness of the limbs, and the existence of rudimentary
parotid glands. I have not had an opportunity of comparing this
specimen with those on which Bibron founded the genus, but I cannot
doubt the specific distinction between them.

DIMENSIONS.

In.

Lin.

Length

of the head and body
. . .
. . .
. . .
. . .
. . .
. . . .
. . .

0

9

of the anterior extremities
. . .
. . .
. . .
. . .
. . .
. . .

0

5

of the posterior extremities
. . .
. . .
. . .
. . .
. . .
. . .

1

1

It was found by Mr. Darwin at Port Desire, and its
habitat is very remarkable. "It is bred in and inhabits water far too
salt to drink."

by Mons. d'Orbigny, and which formed the subject of
Mons. Bibron's description. Mr. Darwin's specimen was taken on the open
plains at Monte Video.

Of the three species of this remarkable genus at
present known, two are inhabitants of Africa, from whence they were
brought by Delalande. As neither of them has as yet been figured, it
was thought desirable that the present opportunity should be taken to
exhibit some of the generic characters, and especially the hard horny
spur on the hinder foot.

This genus is one of those bufonine forms of the
RANIDÆ which irresistibly lead us to doubt the correctness of the
present received arrangement of the anourous Amphibia.

A genus of the Raniform group, nearly allied, as
Mons. Bibron observes, to Scaphiopus, by the structure of
the
hands, which, although without any projecting rudimentary thumb, has a
small process under the skin, along the extreme margin of the first
finger. In common with the genus Bombinator, it has the
opening of the Eustachian tubes so small as scarcely to be detected.

ALSODES MONTICOLA. Mihi.

PLATE XVIII.—FIG. 3.

DESCRIPTION.—Head semi-elliptical, somewhat convex,
with the muzzle nearly perpendicular; vertex smooth. Eyes of moderate
size. Nostrils very small, opening upwards. Tongue broad and rounded
behind, narrowing to a point at the apex, detached at the posterior
part. Palatine teeth in two small approximate patches, between the
posterior nostrils. Openings of the Eustachian tubes scarcely visible.
Extremities of moderate length. The fore feet, with four rather short
toes, connected at the base by a short membrane; the inner toe broad,
and with a slight projection under the skin, along its inner margin;
hinder toes connected as far as the joint of the second and third
phalanges.

The colour of the only specimen in the collection
has become totally changed into a smoky brown by the spirit, but the
following is Mr. Darwin's description

of it when living: "On the centre of the back a
strong tinge of grass-green, shading on the sides into a yellowish
brown; iris coppery."

DIMENSIONS.

In.

Lin.

Length

of the head
. . .
. . .
. . .
. . .
. . .
. . . .
. . . .
. . . .
. .

0

5

of the body
. . .
. . .
. . .
. . .
. . .
. . . .
. . . .
. . . .
. .

1

0

of the anterior extremities
. . .
. . .
. . .
. . .
. . .
. . .

0

9

of the posterior extremities
. . .
. . .
. . .
. . .
. . .
. . .

1

8

Mr. Darwin found this species "in the island of
Inchy, archipelago of Chonos, north part of Cape Tres Montes, from the
same great height as Bufo Chilensis (from 500 to 2500 feet
elevation) under a stone."

GENUS—LITORIA. Bibr.

LITORIA GLANDULOSA. Mihi.

PLATE XVIII.—FIG. 4.

Femoribus
posticè glandulosis; digitis posticis brevitèr
palmatis.

This species agrees in many respects with Litoria
Americana of Bibron. It differs, however, in the toes being much
less palmate, at least according to the generic character given by that
excellent naturalist, and in the existence of numerous thick glands on
the posterior part of the thighs. The very slight degree to which the
extremities of the toes are dilated in the other species of this genus,
and which would at first sight lead to their allocation amongst the
Raniform rather than the Hyliform group, is in the present species
even more strongly exhibited; and it can scarcely be said that any
dilatation exists at all.

The colours in the only specimen brought by Mr.
Darwin are much obscured. The upper parts are apparently of an uniform
brown, the under parts whitish, dotted with brown.

This genus, which considerably resembles Hylodes,
is nevertheless sufficiently distinct from it, in the distribution
of the palatine teeth, in the form of the dilatations of the toes, in
the presence of a small palmar membrane, and some other points. One of
the most remarkable of its characters is the form of the dilatation at
the extremity of the toes; it is very small, transverse, truncated,
and even a little emarginate; in this respect it must be considered as
constituting a very near approach to the family of the RANIDÆ. We are
unfortunately without any information as to the habits of the only
known species which could throw any light upon its relations; but it is
very clear that the dilatations of the toes are not such as to
constitute it a true tree-frog, nor, on the other hand, are
the connecting membranes of sufficient extent to give it the typical
character of the swimming group of these animals.

BATRACHYLA LEPTOPUS, Mihi.

PLATE XVIII.—FIG. 5.

DESCRIPTION.—Head depressed, broad, rounded.
Nostrils small, placed near together. Eyes large, opening considerably
upwards. Tongue nearly round, the posterior part free for about
one-third of its length. Palatine teeth placed in two small oval
groups, placed obliquely, between the posterior nostrils, separated
from each other by a considerable space. Tympanum small, nearly round.
Limbs of moderate length. The toes on all the feet depressed, slender,
the terminal dilatation very small, transverse, truncated; those of the
fore feet connected at the base only, those of the hinder to the union
of the first and second phalanges; of those of the fore feet the third
is the longest, then the fourth, the second, and the first; of the
hinder the fourth is the longest, then the third and fifth equal, then
the second and the first. There are some minute scattered glands on the
posterior part of the thighs.

The only specimen in Mr. Darwin's collection is in
so bad a condition, that it is impossible to say with any certainty
what is its natural colour. It is brown

above, with a lighter band across the head between
the eyes, and there are traces of a longitudinal line down the back;
the limbs are banded with brown and brownish yellow; the under parts
are pale, dotted with brown.

A genus nearly allied to Hylodes, from
which, however, it may at once be distinguished by the palmure of the
hinder toes—which in Hylodes are entirely free—and by the
absence of even the slightest dilatation of their extremities;
offering another example of an osculant form between the HYLIDÆ and the
RANIDÆ.

HYLORINA SYLVATICA. Mihi.

PLATE XIX.—FIG. 1.

DESCRIPTION.—Head broad, rounded, the anterior
margin, from the nose to the lip, nearly perpendicular. Eyes large and
prominent. Tympanum distinct, small, round. Tongue very large,
circular, and entire, the posterior half free. Palatine teeth placed in
a transverse line between the posterior nostrils, scarcely interrupted
in the middle. Skin of the back rugose. Anterior feet with the toes
long, rather slender, united at the base only by a very short membrane,
with round subarticular tubercles, the apex rounded, but not presenting
the slightest expansion. Hinder toes similarly formed, but with the
connecting membrane more conspicuous, and extending along the sides of
the toes nearly to the extremity. Thighs covered on the under and
posterior surface with rather large and distinct glands.

The following is the description of the colouring,
as given by Mr. Darwin from the living specimen. "Above fine grass
green, mottled all over with copper colour, which nearly forms two
longitudinal bands; beneath entirely of a lurid reddish lead colour.
Iris brown."

DIMENSIONS.

In.

Lin.

Length

of the head
. . .
. . .
. . .
. . .
. . .
. . . .
. . . .
. . . .
. .

1

0

of the body
. . .
. . .
. . .
. . .
. . .
. . . .
. . . .
. . . .
. .

1

8

of the anterior extremities
. . .
. . .
. . .
. . .
. . .
. . .

2

1

of the posterior extremities
. . .
. . .
. . .
. . .
. . .
. . .

4

4

Found by Mr. Darwin in the Archipelago of Chonos (S. of Chiloe)
in thick forests.

DESCRIPTION.—Head short, thick, the sides anteriorly
converging towards a nearly right angle, the muzzle rounded. Tongue
nearly cordate, posteriorly emarginate, free for about one-fourth of
its length. Palatine teeth in two oval fasciculi, placed nearly
transversely between the posterior nares, and almost contiguous. Eyes
prominent. Tympanum circular, rather large. Body plump, the sides
nearly parallel for two-thirds of its length. The skin nearly smooth,
but covered with very small inconspicuous granulations over the whole
upper surface, which are rather more obvious on the head. The throat,
the belly, and the inferior surface of the thighs covered with large
prominent granulations. Beneath the lower jaw the granulations are
smaller, and the under surface of the limbs excepting the thighs is
quite smooth. A small fold of skin over the tympanum passes backwards
to the arm; and beneath the throat there are two considerable
transverse folds, one of which is before and the other immediately
behind the arms. Fore feet, with the palms covered with small granular
tubercles, and a tubercle under the joints of the fingers, which are
connected to about one-third of their length. Hinder legs longer than
the head and body by the whole foot and tarsus. The soles tuberculated.
Toes rather short, palmate to half their length.

COLOUR.—The whole of the upper parts are greyish
brown, with a tinge of red, and minutely punctured with black. There
are scattered spots of the latter colour on the back and sides,
assuming somewhat of a longitudinal arrangement, and a broad blackish
grey fascia extends

from the eye backwards to the arm, including the
tympanum, and this fascia is bordered beneath by a white line. The
thighs and legs are barred and spotted with black. The under parts are
yellowish white, excepting under the lower jaw, where it is finely
mottled with black and white.

I received the name of this species from Mons.
Bibron, who had, I believe, applied it to specimens in the Paris
Museum. It was taken by Mr. Darwin at Maldonado, lurking under a stone,
and at Rio Janeiro on palm-trees.

DESCRIPTION.—Head short, thick, the two sides of the
muzzle approaching each other at a rather acute angle, rounded at the
extremity. Eyes rather large and prominent. Tympanum circular, of
moderate size, and very distinct. Tongue entire, rounded, and free
behind, narrowed, and almost angular in front. Palatine teeth in two
oval parcels separated by a very small interval, and placed on a line
with the hinder margin of the posterior nares; the whole of
the back covered with extremely small granules; a slight fold or
elevation of the skin commencing above the posterior margin of the
tympanum, and extending backwards just above the arm, in front of which
it is met by a more considerable one which crosses the throat from side
to side; the under parts covered with large granules; fore feet with
the toes palmated only at the base; hinder ones palmated to four-fifths
of the length.

The colour of this beautiful species is thus given
by Mr. Darwin:—"Above emerald green, beneath white; a silvery white
stripe bordered beneath with a very narrow black line, extends from the
corner of the eye, along the side, to the

thigh; a smaller one at the corner of the mouth; the
posterior surface of the hinder legs and the flanks marked with black
spots. Iris gold coloured; tympanum brown."

DIMENSIONS.

In.

Lin.

Length

of the head and body
. . .
. . .
. . .
. . .
. . .
. . . .
. . .

1

8

of the anterior extremities
. . .
. . .
. . .
. . .
. . .
. . .

1

0

of the posterior extremities
. . .
. . .
. . .
. . .
. . .
. . .

2

8

The young of this species, instead of the bright
green colour of the upper parts, is of a delicate grey with small brown
markings; and a lateral fascia of brown, bordered above and beneath
with a white line, extends from the fore part of the head backwards,
the upper white line nearly to the thigh, the inferior one to the
shoulder. The black spots on the flanks and thighs are but just visible.

This species so nearly resembles the Hyla
pulchella of Mons. Bibron, at least as far as his description
enables me to ascertain its characters, that it was with some
hesitation that I came to the conclusion that they are distinct.
Exclusive, however, of the difference of colour, the back of the
present species is granulated, and the throat still more distinctly so,
whereas the other animal has the skin on the upper parts, as well as on
the anterior part of the throat, quite smooth. The palatine teeth also
appear to be somewhat differently arranged.

Mr. Darwin observes, that this species was found in
numbers in the open grass plains, and likewise in swamps, about
Maldonado, and that they can never ascend trees, as these are entirely
wanting at the places frequented by the Hylæ.

DESCRIPTION.—The head and body are flattened, the
head triangular, slightly truncated in front, but appearing angular
from the skin being produced into a small filiform appendage, standing
forwards from the extremity of the snout. The eyes are lateral,
slightly prominent. Body very slender. Skin perfectly smooth, and
without apparent glands, excepting on the thighs. Fore legs rather
short, reaching quite to the thighs when placed by the side; the toes
almost wholly separate, there being but the rudiment of a connecting
membrane at their base. Hinder legs long, extending forwards beyond the
head by the whole length of the foot; the hinder toes are connected
nearly half their length, and the connecting membrane is thick and
coloured like the rest of the skin.

COLOUR.—The colour varies greatly in different
individuals. The following are the principal variations in the
specimens collected by Mr. Darwin. Above pale iron rust-colour, with a
transverse fascia across the head, a triangular one over the shoulders,
a large broad mark on the loins, and the upper part of the thighs all
of a bright beautiful green. The under side anteriorly rich
chestnut-brown, passing into black posteriorly, with several irregular
snow-white spots, particularly a broad one across the belly, and white
bands across the legs. Another specimen was cream colour above, the
markings darker, and with small spots of green. In one the chestnut
colour beneath was replaced by bright yellow. There is one,
constituting a very distinct variety, in which the upper part is wholly
and almost uniformly dark brown. The female is greenish grey above,
without conspicuous markings.

This is the only known species of the genus, which
was founded by Mons. Bibron upon the specimens collected by Mr. Darwin.
The general slightness and elegance of its form, and its slender
proportions, would lead us to consider it at first sight as rather
belonging to the Ranidæ than the Bufonidæ; but
the
total absence of teeth in the upper maxillary arch, shews that its
proper place is in the latter group. Its form and the length of the
posterior extremities would also prepare us to expect that it can leap
freely, which Mr. Darwin states to be the fact. It inhabits thick and
gloomy forests, and is excessively common in the forest of Valdivia.

Of this species, which has been described under
different names by many naturalists, and the synonymy of which has only
lately been cleared up by Mons. Bibron, there exist numerous specimens
in the collection of Mr. Darwin, who found it at Buenos Ayres, and also
in the Archipelago of Chonos, on the west coast of South America. It is
certainly remarkable that the same species should be found on the
opposite sides of the Continent; but on a careful examination I do not
find any specific distinctions between the specimens from the different
localities. The Prince de Wied has described it as found at Brazil,
under the name of Bufo cinctus, and it is also well known as
having been repeatedly procured in Peru and in Chile; but Mons. Bibron
has in his work considered them all as belonging to but one species.
The following account of its habits as given by Mr. Darwin is very
curious and interesting:—"These Toads are exceedingly abundant all
over the treeless damp mountains of granite, crawling about, and eating
during the daytime, and making a noise similar to that which is
commonly used in England to quicken horses. Many of them on being
touched close their eyes, arch their back, and draw up their legs (as
if the spinal marrow was divided), probably as an artifice. They are
remarkable from their curious manner of running like the
Natter Jack of England; they scarcely ever jump, neither do they crawl
like a toad, but run very quickly. Their bright colours give them a
very strange appearance. They abound at an elevation of 500 to 2500
feet."

This curious little species has been described by
Weigman under the present name,—by Tschudi under the generic name of Chaunus,
and fully by Bibron, who retained the name originally given to it
by Weigman. It now remains only to correct, from Mr. Darwin's notes,
some points respecting the colours, which had been mis-stated in
consequence of the action of the spirit in which the specimen had been
preserved. The colour of this curious miniature representation of a
Toad, is "ink black," excepting the palms and soles of the feet, a
large transverse spot across the posterior part of the abdomen, two
smaller ones near the middle, and in some specimens a few scattered
little spots, all of the most intense vermilion red. There is one
specimen from Bahia Blanca which has also some small "buff-orange"
spots on the upper part.* Mr. Darwin observes that "the appearance of
the vermilion colour is as if the animal had crawled over a newly
painted board;" and he adds—"This Toad inhabits the most dry and sandy
plains of Bahia Blanca, where there is no appearance of water ever
lodging." The other specimens were taken at Maldonado, where it
inhabits the sand-dunes near the coast. Mr. Darwin threw one into a
pool of fresh-water, but he found it could hardly swim, and he thinks,
if unassisted, it would have been soon drowned.

This species is diurnal in its habits, and may be
daily seen under a scorching sun, crawling over the parched and loose
sand. M. D'Orbigny brought specimens from Monte Video.

little outwards. Eyes rather large, the upper
eyelids forming perfect flaps, which entirely cover the eyes. Body
rounded, very broad. The shoulders and thighs wholly concealed by the
skin of the body. Limbs very short. The anterior feet very broad. The
toes somewhat depressed, very short, bordered with a fold of skin.
Hinder feet with the toes more depressed and more distinctly bordered.
Back covered with small glands.

COLOUR.—The colour of the upper surface
is dark olive, becoming lighter at the sides, and having numerous dark
brown spots, which are round, oval, elliptical, or irregular, of very
various sizes, placed somewhat symmetrically, and each bordered with a
whitish or yellow line. Beneath pale, excepting the throat, which is
black.

I have ventured to consider this remarkable
amphibian as specifically distinct from U. marmoratum of
Bibron; a conclusion to which I have been almost imperatively led, by
the fact of its inhabiting a different hemisphere from all known
specimens of that species. The other was found by M. Leschenault in the
interior of the peninsula of India: the specimen from which the
present description is taken was obtained by Mr. Darwin at Buenos
Ayres. Notwithstanding the similarity of the two species, which is so
great as to have led Mons. Bibron to consider them as identical, I
could not assent to such an anomaly as the existence of an animal, at
once so rare and possessed of such limited powers of locomotion, in two
regions so widely remote. I have not the opportunity of comparing the
specimens of the former species with the present, but, even from Mons.
Bibron's description, I believe that I can discover sufficient
discrepancies between the animals, to bear me out in the view I have
taken. These discrepancies I venture to place in the following tabular
view, and leave zoologists to form their own conclusions.

AMONGST the Reptiles and Amphibians obtained by Mr.
Darwin, in the Voyage of the Beagle, there are several of great
interest, not merely on account of their novelty as newly discovered
species, of which there are nearly thirty, or as forming the types of
genera not previously known, or of any remarkable peculiarity of form,
structure, or habit, although in all these respects many of them are
highly interesting; but more particularly as serving to establish or
confirm several points connected with their geographical distribution.

From the structure of most of these animals and
their consequent habits of life, circumscribed as they are for the most
part in their locomotive powers, it might reasonably be predicated that
they would, upon the whole, exhibit as distinct examples of
restriction, with regard to their geographical boundaries, as any class
of vertebrated animals; and that the intervention of seas and of
mountains would be sufficient to limit the range of a species. Such is
in fact usually the case; and not only is the same species not found in
the Old and New Continents, but, with very few exceptions, not even on
the opposite sides of the South American Continent, in which range Mr.
Darwin's discoveries have principally been made. The occurrence,
however, of Bufo Chilensis at Rio Janeiro and at Buenos
Ayres
on the eastern, and at Valparaiso and the Archipelago of Chonos on the
western side of the continent, shows an extent of distribution
exceedingly unusual if not absolutely unparalleled in this family. It
is, however, still possible that further and more extended researches
into the characters of the animals in question, and an examination of
individuals from each locality at various ages, may prove that there
are two species, which have been confounded with each other, and the
anomaly may thus be removed.

But although the circumscribed range of a species
may be accounted for by the reasons above mentioned, and others of a
restrictive nature, it is not so easy to refer to any known or obvious
cause the remarkable fact of a whole genus, consisting of numerous
species, being thus geographically limited. Yet this is a

well-known and very common circumstance with regard
to several groups of animals. In our present researches there exists a
remarkable example of this fact in the genus Proctotretus,
consisting,
as is now known, of at least fourteen species, all inhabiting the
western coast of South America. These facts, interesting as they are,
have never been sufficiently investigated, although, it must be
confessed, there are so many anomalies in relation to this subject,
that we must despair of ever reducing the facts in question to any
thing like fixed laws.

The close approximation of the Raniform and Hyliform
groups of the Anourous Amphibia is strikingly illustrated by several
new forms obtained by Mr. Darwin, which are so perfectly osculant
between the two families, that it is difficult to assign them a decided
location. And the addition of some bufonine forms in the family Ranidæ,
as at present constituted, and on the other hand of some amongst
the Bufonidæ, which are no less raniform in their general
structure and habits, render it increasingly probable that the single
character of the presence or absence of superior maxillary teeth, must
be considered as insufficient to constitute alone a natural distinctive
family character. There are several minor points bearing upon the
natural arrangement of the Anourous Amphibians, which are illustrated
by the characters of some of the species now first described, which
will doubtless at some future time assist in the construction of a
classification of these animals, bearing at least a nearer
approximation to their natural arrangement than any that has hitherto
been promulgated.

The Ophidians have been placed in the hands of Mons.
Bibron, who is at the present time engaged in completing his admirable
history of Reptiles, by the publication of those volumes which are
devoted to this order; and it must be considered a fortunate
circumstance that the delay which has taken place in the appearance of
that portion of his labours, has thus afforded the opportunity of
embodying in so perfect a work, the numerous discoveries of Mr. Darwin
in this particular department of Erpetology.